Global Navigation Satellite Systems (GNSS) as the one currently available GPS or the Galileo system in the future have found a great diversity of applications. Among them their use to monitor localization of mobile agents (vehicles, individuals, assets etc) have encountered ample proliferation. The basic concept is to make available in a central platform the position information derived from GPS and to exploit that information with different application specific purposes. Examples of those applications are Automatic Vehicle Location, Fleet Management Systems, Road Pricing or Automatic Tolling Applications.
Some of those applications intend to use position information not only to improve operational efficiency but also as a proof to elucidate economical or liability issues between parties. In those cases each position data record must be guaranteed to be within required accuracy limits otherwise affected (economically or liability) party could reject validity of information. In present systems it is assumed that error of position information is within required limits for the application for which it is used based on errors statistics. However the user of the information does not have any guarantee that the error in a particular position record is within specific boundaries. In other words although error statistics could be within acceptable limits, one particular position record may have an error out of acceptable limits for the application.
The system described in present invention solves this problem, providing the user with the guarantee that if a position record is positively flagged its error is within specified limits (Integrity guarantee).
One key issue for the application feasibility is the link between the integrity risk and the legal concept of evidence: The concept of evidence has to be understood as a probabilistic parameter and it is to be legally defined what is the failure probability that a Court can accept as evidence. While the proposed system could be tuned to any legal conclusion, it is initially anticipated based on existing jurisprudence, that values of 10−7 as usually defined by Safety Critical Applications are well below typical values used legally: statistics of judicial errors together with jurisprudence in probability related fields (as it is the case of the use of DNA evidences to demonstrate the authority of a crime or the paternity).
Present invention is supported and is a direct application of a two innovative concepts and methods:                [1] A method to guarantee GNSS positioning Integrity performance under non-controlled environments. This new method allows assuring within a probability level that each individual position data is within certain error limits when it is positively flagged. This new method is itself subject of another patent application being presented in parallel, titled “GNSS Navigation Solution Integrity in non-controlled environments (Ref [3]).        [2] Application of the Integrity concept in the Legal or commercial field. Integrity Service as provided by Space Based Augmentation Systems (SBAS) (WAAS, EGNOS, MSAS . . . ) and by future Global Navigation Satellite Systems (GNSS) such as Galileo are conceived and driven by its use for safety critical applications mainly Civil Aviation. However, the Integrity defined as “. . . a measure of the trust that can be placed in the correctness of the information supplied by the system . . .” is understood to have an essential value for other non “safety-critical” navigation applications where the use of the navigation solution is to be applied with some purposes that imply certain liabilities either commercial, legal or government policy implementation ones.        
The present invention provides the basis for the exploitation of a navigation solution with guaranteed integrity for the so-called “liability-critical” applications i.e. those applications where the use of the provided solution is associated to a certain liability and hence, a guaranteed navigation solutions (with errors properly bounded) is essential.
This concept is based upon the following rationale:                [a] In the legal, contractual and commercial fields there are situations where GNSS position or velocity data is used as evidence to proof or resolve a particular issue.        [b] GNSS position or velocity data is subject to errors, this means that the difference between the provided position or velocity and the actual position and velocity is not null and its magnitude cannot be predetermined.        [c] GNSS position and velocity accuracy defined as the statistically determined standard deviation of GNSS position and velocity error does not guarantee that an individual GNSS position and velocity data be within certain error boundaries.        [d] The Integrity concept has been used for a long time in safety critical navigation sensors, and in particular in GNSS safety critical application, where GNSS position or velocity error can put into risk the life of individuals. This magnitude establishes the probability for the measurement device to provide data with error superior to pre-established error boundaries without informing the user of such a situation.        [e] As a result of previous points, it is not the statistical determined accuracy of the measurement device but the Integrity of it what should determine if a particular GNSS position or velocity can be or not used as evidence.Mentioned Integrity Requires:        They use a Signal In Space with built-in integrity as defined by ICAO GNSS Requirements.        They implement specific integrity algorithms as the ones identified in [1].        MU has been subject to a “type approval” process that legally ensures that they have been designed and developed in line with the required procedures.        An appropriate contractual and legal framework is established among the different actors (GNSS service provider, certification authority, users and mobile agent).        